Although, in the case of a "Gish Gallop" you can very well argue against the method, which is not so much about presenting evidence as it is about keeping you from presenting your side of issue.
If I present my argument in a manner that intellectually dishonest and/or distorts your position, you can call me out on that without going ad hominem.
If I present my argument in a manner that intellectually dishonest and/or distorts your position, you can call me out on that without going ad hominem.